The present invention relates to a level conversion circuit for use in a semiconductor integrated circuit device and, more particularly, to a level conversion circuit for converting a level of a signal from its small amplitude to large amplitude at a high speed.
In the prior art level conversion circuits which are fully explained later for assisting the understanding of the present invention, the ON and OFF operation at the side of an N-channel MOS transistor which forms the CMOS inverter is effected through the N-channel MOS transistor current mirror circuit which responds to a P-channel MOS transistor switch of either a source input type or a gate input type and, consequently, the ON and OFF operation involves a large time day. Also, when the output is of a low level, the current mirror circuit of the N-channel MOS transistors turns on and this causes the flow of a through current. These problems which are also fully explained later are regarded as presenting serious problems to be solved for the realization of a circuit which can operate at a high speed and at a low power consumption.